Optical systems have in the past been constructed with discrete optical components such as optical fibers, mirrors, lenses, filters, detectors, lasers, light emitting diodes, wave guides and optical sensors. These components have been extensively used and may be utilized in many types of applications. However, there are instances, particularly with the current emphasis on miniaturization, where discrete components are often too bulky and too difficult to interconnect.
Some of these obstacles have been overcome by the development of integrated optics, where several different optical components are made or mounted directly on a substrate. A large variety of miniature components and systems has been made possible by this approach. A result of this type of miniaturization has in some instances greatly increased manufacturing complexity and reduced flexibility which prevents the circuit designer or engineer from rapidly changing designs.
It has been common to employ three-dimensional structures for interconnecting optical fibers in predetermined fashions. Examples of such three-dimensional structures are found in U.S. Pat. Nos. 4,339,290, 4,498,731 and 4,130,345. In the first of the above three patents, and in U.S. Pat. No. 4,483,582, building blocks are employed in optical systems where the adjacent building blocks are aligned by physical contact with each other and not by a precise interconnection with a master substrate or equivalent framework.
Different means have been devised for holding optical fibers in predetermined locations. Some of these use a polymeric relief pattern such as disclosed in U.S. Pat. Nos. 4,339,290 and 4,164,364. These patterns may be photolithographically created in thick film patterns. These prior art thick film patterns are only used for alignment of optical fibers and have no other functions.
The optical systems of U.S. Pat. Nos. 4,306,765, 4,130,343, and the first three patents mentioned above, disclose semi-reflective or transmissive layers on or in conjunction with optical fiber surfaces. The use of such layers is well known in optical fiber systems. However, one problem with several of the prior art multiple element systems of the types mentioned above is that because the components depend upon accurate surface treatment for proper alignment, errors can be cumulative. In this way, a system so constructed can be very inaccurate in certain aspects of its alignment due to such cumulative errors.
An example of a micro-optical building block system is shown in U.S. Pat. No. 4,789,214. This patent shows the use of predetermined relief patterns which facilitate interconnection or alignment of building block elements. Specifically, it implies a flat master substrate with building blocks having a flat surface with mating relief patterns on them. This structure is somewhat limited in its flexibility because of the fact that at least one of the mating or confronting surfaces have predetermined relief patterns and are flat.